Qualitative and Quantitative Pcr Methods For Detection of Foods Containing Genetically Modified Soybean and Corn.
Genetically modified organisms (GMOs) can be defined as organisms in which their genetic materials have been altered in the ways that does not occur naturally by mating or natural combination. Polymerase chain reaction (PCR) method is used to detect genetically modified events in foods. The spec...
Saved in:
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English English |
| Published: |
2006
|
| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/6735/1/FSTM_2006_29.pdf |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Genetically modified organisms (GMOs) can be defined as organisms in
which their genetic materials have been altered in the ways that does not
occur naturally by mating or natural combination. Polymerase chain reaction
(PCR) method is used to detect genetically modified events in foods. The
specific objectives of this study are to establish a sensitive, robust and rapid
method for the detection of genetically modified events by using PCR and to
conduct a preliminary survey for distribution of foods derived from
genetically modified events in Malaysia.
The two critical factors that were taken into account to achieve these objectives
are the applicability of different DNA extraction methods for each kind of
samples and PCR amplification conditions. Three different DNA extraction
methods have been tested on soy, corn, potato and tofu (as a processed food).The DNeasy method as in a widely used commercial kit, Wizard method
(Hemmer, 1997) and Cetyl-trimethyl ammonium bromide (CTAB) method
(Jankiewicz et al., 1999) were evaluated in this study. The yield and purity of
DNA were examined and compared. Quantification was accomplished by
measuring UV absorbance at 260 nm and the suitability of DNA for PCR was
tested. The results showed that there are sigruficant differences between the
methods used. CTAB, Wizard and DNeasy methods produced DNA with
ratio of A260/A280 range from 1.2 to 1.6, 1.9 to 2.2 and 1.7 to 1.9, respectively.
However, the DNeasy method gave the optimum yield of DNA of high purity
and was less time consuming. The primer pairs used for confirmation of the
endogenous genes in the respective samples (Lectinl / Lectin6 for lectin gene in
soya, Zein n-3' / Zein n-5' for zein gene in maize and PssOl n5'/PssOl n-3' for
patatain gene in potato) produced the expected size of 318, 157 and 216 base
pair, respectively.
The results of this study showed that 18 out of 85 soy samples were
contaminated by at least one of three introduced genetic elements consisting
35s promoter, Nopaline Synthase terminator and the structural gene of 5-
enolpyruvylshikimate-3-phpsphate-synthas. Quantitative analysis of the 18
positive genetically modified soy samples showed that, seven samples
contains 0.1 - 0.5% Roundup Ready Soy, four samples contains 0.5 - 1.0%
Roundup Ready Soy and seven of them contains 1.0 - 2.0% Roundup Ready Soy.In contrast, none of the 52 was positive with these assays. Therefore they were
categorized as non-GM products.
These results revealed that PCR amplification method provides the key
advantages of high sensitivity, robust and rapid operation whilst providing
the requisites of careful experimental design that avoids both false-negative
and/or false-positive results. Seven primer pairs (LECl/LEC6; Zein n-
3'/ Zein n-5'; PssOl n-5'/ PssOl n-3'; P35S 1-5'/ P35S 2-3'; HA-NOSll8-F/ HANOSllaR,
Cryl(Al)/Cryl(M) and RRO1/ RRO4) chosen in this study
produced an expected size of 318, 157, 216,101, 118, 107 and 356 base pair,
respectively, fulfilling the product-size requirement and completed the whole
detection procedure of GM events in food samples. |
|---|